Coupler lock



FIG. 1 is a perspective view of a coupler lock showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a first side view thereof;

FIG. 5 is a second side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The features shown in broken lines in the drawing figures are for the purpose of illustrating portions of the coupler lock and form no part of the claimed design. 

CLAIM The ornamental design for a coupler lock, as shown and described. 